JP4501274B2 - Automatic brake control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic brake device that automatically performs a braking operation, and is suitable, for example, for brake control during automatic traveling.
[0002]
[Prior art]
As an automatic brake device used for automatic traveling, for example, a brake that adjusts the amount of brake fluid that flows to the wheel cylinder (hereinafter referred to as W / C) side by adjusting the degree of opening of a solenoid valve according to the amount of energization. An electric brake device that generates a braking force by energizing a device or an actuator for driving a brake (for example, a motor for moving a brake pad in the direction of a brake disk) is used. These brake devices generate a braking force according to the magnitude of the command current by supplying the command current determined to the electromagnetic valve or the brake driving actuator.
[0003]
In the brake control during automatic traveling by the automatic brake device having such a configuration, for example, a brake output larger than the brake output required for the flat road is set so that the vehicle does not slide down on the slope, In any case, a sufficient braking force can be obtained.
[0004]
[Problems to be solved by the invention]
However, because the brake output is set to be large regardless of whether the road is flat or sloped, there is a problem that the durability of the brake parts is reduced, and a large command current is required, resulting in an increase in power consumption. Is generated.
[0005]
An object of the present invention is to provide an automatic brake device that can solve the problem of a decrease in durability of a brake component and the problem of an increase in power consumption while preventing slippage on a slope.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, there is provided an instruction current calculation means (12) for calculating an instruction current corresponding to the target brake pressure, and the brake driving actuator (6) is driven by the instruction current. Thus, the automatic brake device configured to generate the target braking force is provided with acceleration / deceleration detection means (3) for detecting the acceleration and deceleration of the vehicle, and is adjusted when the vehicle is stopped. The detection result of the speed detection means is fed back to the indication current calculation means, and the indication current is adjusted according to the detection result of the acceleration / deceleration detection means.
[0007]
Thus, by feeding back the detection result of the acceleration / deceleration detection means to the command current calculation means, the gradient of the road surface on which the vehicle is stopped is fed back, depending on whether the road surface is a flat road or a slope. Brake pressure can be generated. As a result, it is possible to solve the problem of a decrease in durability of the brake parts and the problem of an increase in power consumption while preventing slipping down on the slope.
[0008]
Specifically, with the absolute value calculating means for calculating the absolute value of the acceleration and deceleration that is detected by the pressure deceleration detecting means (9), when the vehicle is stopped, is calculated by the absolute value calculation means The absolute values of acceleration and deceleration are fed back to the command current calculation means, and the command current is adjusted according to the absolute values of acceleration and deceleration.
In the first aspect of the invention, there is provided an integral calculation means (10) for integrating the absolute values of acceleration and deceleration with respect to time, and the command current calculation means is in accordance with a calculation result by the integral calculation means. It is characterized in that the command current is adjusted.
Thus, the brake pressure according to the slope of the slope can be set by increasing the command current according to the calculation result by the integral calculation means.
In this case, for example, as shown in claim 2, there is provided an initial brake pressure calculating means (8) for calculating a reference brake pressure required when the vehicle is stopped on a flat road, and the vehicle is stopped. In this case, a value obtained by adding the calculation result of the integral calculation means to the reference brake pressure calculated by the initial brake pressure calculation means may be set as the target brake pressure.
[0009]
The invention according to claim 3 is characterized in that the command current is set larger as the absolute values of acceleration and deceleration are larger by the command current calculation means. The absolute values of acceleration and deceleration indicate the slope of the slope. For this reason, the brake pressure according to the slope of the slope can be set by increasing the command current as the absolute value increases.
[0012]
In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 shows a schematic configuration of an automatic brake device according to an embodiment of the present invention. Hereinafter, based on FIG. 1, the structure of the automatic brake device in this embodiment is demonstrated.
[0014]
The automatic brake device includes a wheel speed sensor 2a that detects a wheel speed signal corresponding to the wheel speed of each wheel (left front wheel FL, right front wheel FR, left rear wheel RL, right rear wheel RR) 1a, 1b, 1c, 1d. 2b, 2c, and 2d, and an acceleration sensor 3 as acceleration / deceleration detecting means for detecting a signal corresponding to the longitudinal acceleration of the vehicle.
[0015]
The automatic brake device also includes a cruise computer 4 used for automatic traveling control, and brake control electronics to which detection signals from the wheel speed sensors 2a to 2d and the acceleration sensor 3 and control signals from the cruise computer 4 are input. A control device (hereinafter referred to as a brake control ECU) 5 and a brake drive actuator 6 controlled by the brake control ECU 5 are provided.
[0016]
The cruise computer 4 performs automatic travel control such as engine control and brake control so as to keep the distance from the preceding vehicle constant during cruise control on, for example, an expressway. In the case of the present embodiment, the cruise computer 4 serves to send a signal related to the target deceleration calculated for brake control to the brake drive ECU 5. A signal regarding the target deceleration sent from the cruise computer 4 is used for controlling the automatic brake device.
[0017]
The brake drive ECU 5 calculates the command current when the vehicle is running and when the vehicle is stopped, and outputs the calculated command current to the brake drive actuator 6. Specifically, the brake drive ECU 5 is configured as shown in FIG.
[0018]
As shown in FIG. 2, the brake control ECU 5 includes a running brake pressure calculation unit 7, an initial brake pressure calculation unit 8, an absolute value calculation unit 9, an integration calculation unit 10, a switch unit 11, and an instruction current calculation unit 12. Is provided.
[0019]
The running-time brake pressure calculation unit 7 calculates the brake pressure when the vehicle is running, and is a brake that is required to obtain the target deceleration based on a signal related to the target deceleration input from the cruise computer 4. Calculate the pressure. That is, during vehicle travel, brake control in normal cruise control is performed.
[0020]
The initial brake pressure calculation unit 8 calculates a brake pressure when the vehicle is stopped, and calculates a reference brake pressure required when the vehicle is stopped based on a signal related to a target deceleration input from the cruise computer 4. . This reference brake pressure corresponds to, for example, the brake pressure required when the road surface when the vehicle is stopped is a flat road. The initial brake pressure calculation unit 8 corresponds to initial brake pressure calculation means.
[0021]
The absolute value calculator 9 calculates the absolute value of the acceleration / deceleration based on the detection by the acceleration sensors 2a to 2d. The absolute value calculation unit 9 detects the slope of the road surface on which the vehicle is stopped. That is, when the road surface on which the vehicle is stopped is a flat road, output due to the influence of gravity cannot be obtained from the acceleration sensors 2a to 2d. However, when the road surface is a slope, the acceleration sensors 2a to 2d are Gravity according to the gradient is applied, and outputs due to the influence of gravity are obtained from the acceleration sensors 2a to 2d. Therefore, it is possible to detect the gradient of the slope based on the detection signals from the acceleration sensors 2a to 2d. Become. The absolute value calculation unit 9 corresponds to absolute value calculation means.
[0022]
The integration calculation unit 10 integrates the calculation result in the absolute value calculation unit 9. The calculation result in the integral calculation unit 10 is added to the calculation result in the initial brake pressure calculation unit 8. The integration calculation unit 10 corresponds to integration calculation means.
[0023]
The switch unit 11 is switched according to the vehicle speed, specifically according to whether or not the vehicle is stopped. When the vehicle is not stopped (that is, when the vehicle is traveling), the switch unit 11 is traveling. The calculation result of the brake pressure calculation unit 7 is adopted, and when the vehicle is stopped, the sum of the calculation results of the initial brake pressure calculation unit 8 and the integration calculation unit 10 is adopted.
[0024]
The command current calculation unit 12 uses the calculation result of the running calculation unit 7 or the calculation result of the initial brake pressure calculation unit 8 and the integration calculation unit 10 as a target brake pressure, according to the target brake pressure. Calculate the indicated current. An instruction current having a magnitude corresponding to a calculation result by the instruction current calculation unit 12 is caused to flow through the brake driving actuator 6. The command current calculation unit 12 corresponds to command current calculation means.
[0025]
For example, in the case of a hydraulic brake, the brake driving actuator 6 adjusts the degree of opening of the electromagnetic valve according to the energization amount so that the brake fluid flows to the wheel cylinder (hereinafter referred to as W / C) side. In the case of an electric brake, it is constituted by a motor for moving the brake pad in the direction of the brake disc. The brake driving actuator 6 is driven based on an instruction current output from the brake driving ECU 5 and generates a braking force according to the magnitude of the instruction current.
[0026]
Next, FIG. 3 shows a flowchart of automatic brake control executed by the brake drive ECU 5 provided in the automatic brake device having the above-described configuration, and details of the automatic brake control will be described based on this drawing.
[0027]
First, in step S100, it is determined whether or not the vehicle is stopped. This process is performed, for example, depending on whether or not the wheel speed is 0 based on the detection results of the wheel speed sensors 2a to 2d.
[0028]
If a negative determination is made in step S100, the process proceeds to step S110. In this step, the running brake pressure calculation unit 7 calculates the running brake pressure based on the signal related to the target deceleration sent from the cruise computer 4. Thereby, the target brake pressure required for achieving the target deceleration is calculated. Then, the process proceeds to step S150.
[0029]
On the other hand, if an affirmative determination is made in step S100, the process proceeds to step S120, and the absolute value calculation unit 9 calculates the absolute value of the acceleration / deceleration from the detection result of the acceleration sensor 3. Thus, when the road surface on which the vehicle is stopped is a flat road, the acceleration sensor 3 is not affected by gravity and the absolute value of acceleration / deceleration is 0. When the road surface is a slope, the acceleration sensor 3 The effect appears, and the absolute value of acceleration / deceleration according to the slope of the slope is obtained.
[0030]
Next, it progresses to step S130 and the integral calculation part 10 integrates the acceleration / deceleration absolute value calculated by step S120 with respect to time. When this integral calculation is performed, if the road surface on which the vehicle is stopped is a flat road, the integral value of the acceleration / deceleration absolute value becomes 0 even if time elapses. As a result, the integrated value of the acceleration / deceleration absolute value increases with the passage of time.
[0031]
Subsequently, the process proceeds to step S140, where the initial brake pressure calculation unit 10 calculates the initial brake pressure based on the signal relating to the target deceleration sent from the cruise computer 4, and the calculation result is subjected to step S130. Add the integral value of the acceleration / deceleration absolute value obtained in step. As a result, the reference brake pressure required when the vehicle is stopped is calculated, and if the road surface on which the vehicle is stopped is a slope, the integral value of the acceleration / deceleration absolute value is added, and the vehicle is stopped. A target brake pressure corresponding to the type of road surface is calculated. Then, the process proceeds to step S150.
[0032]
In step S150, the command current calculation unit 12 calculates a command current value required to obtain the target brake pressure based on the target brake pressure obtained in step S110 or step S140. Thereafter, the process proceeds to step S160, and the command current calculated in step S150 is output to the brake driving actuator 6.
[0033]
By the above processing, automatic brake control is performed while the vehicle is running and stopped. Timing charts when this control is executed are shown in FIGS. 4A and 4B, respectively, when the traveling road surface is a flat road or a slope.
[0034]
As shown in FIG. 4A, when the vehicle traveling road surface is a flat road, first, a target brake pressure corresponding to the target deceleration is calculated during traveling, and then an instruction corresponding to the target brake pressure is calculated. The current is calculated and output to the brake driving actuator 6. For this reason, the vehicle speed decreases according to the target deceleration, and the vehicle is stopped. At this time, since the road surface on which the vehicle is stopped is also a flat road, the acceleration sensor 3 is not affected by gravity, and the acceleration / deceleration absolute value becomes 0. Therefore, only the initial brake pressure becomes the target brake pressure, and the vehicle is stopped. A constant brake pressure is applied.
[0035]
On the other hand, as shown in FIG. 4B, when the vehicle traveling road surface is a slope, first, as in the case of the flat road, the target brake pressure and the instruction current corresponding to the target deceleration during traveling are first obtained. Calculated and output to the brake driving actuator 6. As a result, the vehicle speed is reduced according to the target deceleration, and the vehicle is stopped. At this time, since the road surface on which the vehicle has stopped becomes a slope, the influence of gravity appears on the acceleration sensor 3, and an acceleration / deceleration absolute value corresponding to the slope of the slope is obtained. For this reason, the amount obtained by adding the integral value of the acceleration / deceleration absolute value to the initial brake pressure becomes the target brake pressure, and the target brake pressure increases with time while the vehicle is stopped.
[0036]
In this way, when feedback control based on the detection signal of the acceleration sensor 3 is performed and the road surface on which the vehicle is stopped is a flat road, excessive braking pressure is not generated, but when the road surface is a slope. The brake pressure to be generated is increased as compared with the case of a flat road. For this reason, it is possible to solve the problem of a decrease in durability of the brake parts and the problem of an increase in power consumption while preventing slipping down on the slope.
[0037]
Moreover, since it is changing the brake pressure to increase based on the gravity concerning the acceleration sensor 3 when it is a slope, the increase amount of a brake pressure can be changed according to the gradient of a slope. For this reason, it is possible to prevent slipping down on the slope more suitably, and it is possible to solve the problem of reduced durability of the brake parts and the problem of increased power consumption.
[0038]
In the above description, the integral value of the acceleration / deceleration absolute value is always added to the initial brake pressure. However, if the vehicle stop time is long and the target brake pressure is excessive, the upper limit value is set. It is also possible to prevent the target brake pressure from becoming excessive by providing a setting means and providing an upper limit value for the target brake pressure as shown by the dotted line in FIG.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an automatic brake device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a specific configuration of a brake drive ECU 5 shown in FIG. 1;
FIG. 3 is a flowchart showing details of an automatic brake control process executed by the brake drive ECU 5 shown in FIG. 2;
4 is a timing chart when the automatic brake control process shown in FIG. 3 is executed, (a) is a timing chart when traveling on a flat road, and (b) is when traveling on a slope. It is a timing chart.
[Explanation of symbols]
2a to 2d ... wheel speed sensor, 3 ... acceleration sensor,
4 ... cruise computer, 5 ... ECU for brake drive,
6 ... Actuator for brake drive, 7 ... Brake pressure calculation unit during travel,
8 ... Initial brake pressure calculation unit, 9 ... Absolute value calculation unit, 10 ... Integration calculation unit,
12 ... Indicated current calculation unit.

Claims (3)

An instruction current calculation means (12) for calculating an instruction current according to the target brake pressure is provided, and a target braking force is generated by driving the brake driving actuator (6) by the instruction current. Automatic brake device
Acceleration / deceleration detecting means (3) for detecting acceleration and deceleration of the vehicle;
Absolute value calculating means (9) for calculating the absolute values of acceleration and deceleration detected by the acceleration / deceleration detecting means,
When the vehicle is stopped, the absolute values of the acceleration and deceleration calculated by the absolute value calculation means are fed back to the command current calculation means, and the command current is determined according to the absolute values of the acceleration and deceleration. It is adapted to adjust,
Furthermore, an integral calculation means (10) for integrating the absolute values of the acceleration and deceleration with respect to time is provided,
The automatic brake device according to claim 1, wherein the command current calculation means adjusts the command current according to a calculation result by the integration calculation means . Initial brake pressure calculating means (8) for calculating a reference brake pressure required when the vehicle is stopped on a flat road;
When the vehicle is stopped, a value obtained by adding the calculation result of the integral calculation means to the reference brake pressure calculated by the initial brake pressure calculation means is set as the target brake pressure. The automatic brake device according to claim 1 , wherein 3. The automatic brake device according to claim 1, wherein the command current calculation unit sets the command current to be larger as the absolute values of the acceleration and deceleration are larger.

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